Crankcase ventilating system



June 7, 1938. w. w. LOWTHER CRANKCASE VENTILATING SYSTEM Filed Jan. 28,1937 Patented June 7, 1938 UNITED STATES El iii CRANKCASE VENTILATINGSYSTEM Wilfred W. Lowther, St. Paul, Minn., assignor to DonaldsonCompany, Inc., St. Paul, Minn, a corporation of Minnesota ApplicationJanuary 28, 1937, Serial No. 122,755

12 Claims.

My present invention relates to crank-case ventilating systems and thelike and is particularly directed to means for keeping clean and clearof sediment or other accumulations small air passages or conduits. Thepresent invention is the result of an experience with the crank-caseventilating system disclosed and claimed in my prior Patent No.2,060,883 of date November 17, 1936. In the apparatus of said patent itwas found necessary to employ very small or restricted air passages forlimiting the flow of air to and from the crank-case of the engine underthe action of varying suction or partial vacuum produced in the actionof supplying hydro-carbon vapors to the engine cylinders; and it isfurther found that under continued use these small air passages wouldbecome clogged with tar-like deposits from the hydro-carbon vapors. v

The present invention provides an extremely simple and highly efficientdevice for automatically cleaning out these restricted passages andkeeping the same clear of the above and all other deposits. The improvedclean-out device works through the restricted passage and is subject tointermittent movements produced by varying action of partial vacuum orsuction. In preferred form each cleanout device comprises a stem workingthrough the passage and provided with a weighted lower end and with ahead.

In the drawing severalof these clean-out devices are shown as applied ina crank-case ventilating system of the type disclosed in my priorpatent; and in the description of this application of the inventioncertain parts that are identical or correspond to parts of the saidpatent will be indicated by like characters. In the accompanying drawingwhich illustrates theinvention, like characters indicate like partsthroughout the several views.

Referring to the drawing:

Fig. 1 is a side elevation with some parts broken away and some parts invertical section, showing the invention applied to a Ford V 8 engine;

Fig. 2 is a fragmentary detail showing the in,- vention on an enlargedscale and in section, certain of the parts shown in section at the upperleft-hand portion of Fig. l; and

Fig. 2a is a section taken on the line 2a-2a of Fig. 2. v

The following step, as hereinafter pointed out, is substantially arepetition of the description of the mechanism of my prior patent.

The cylinder block of the engine, which, as is well known, includesangularly disposed sections, each containing ,a bankuof four cylinders},is

indicated as an entirety by 3'. The crank shaft is indicated as anentirety by 4 and the crankcase, which latter serves as an oilreservoir, is indicated by 4'. The carburetor. indicated by 5 and whichis of the well-known double Venturi 5 tube type, is provided with athrottle valve 5', for each Venturi tube thereof. The carburetor isconnected to the engine cylinders through an integrally formed pair ofintake manifolds 6 and 6', each of which manifolds. extends from an 10opposite throttle valve controlled Venturi tube and distributesexplosive mixture to an opposite bank of cylinders 3. The manifolds 6and 6' of the Ford V 8 engine, are integrallyformed in a plate 1 thatextends between opposite block sections and serves to close theintermediate upper portion of the crank-case 4. In carrying out theinvention, the oil filler tube 1' of the crankcase, which is normallyopen to the atmosphere,

is sealed by a screw-threaded cap or the like 8. The carburetor 5 issupplied with gasoline from the supply tank, not shown, through a feedline I!) having interposed therein the customary fuel pump II. This fuelpump is operated from the engine's cam shaft 9.

The intake of the engine is preferably provided with an air cleaner forremoving all impurities from the air before delivery to the engine, butinsofar as the invention is concerned, this air cleaner may take variousdifierent forms.

In the arrangement illustrated, the clean air discharge tube of the aircleaner I8 is telescoped to the upper end of the upstanding air intakeneck or tube 9a of the carburetor 5.

Venting ofthe crank-case and circulation of the air therethrough isbrought about by independent connection of points of the engine's intakeat opposite sides of the throttle valves 5' to the crank-case at pointsabove the maximum oil level therein. Since it is desired to circulate 40only clean air through the crank-case, the connections above noted arepreferably taken from the intake on the engine side of the air cleaner.I

In the preferred application of the invention to the Ford V 8 engine,and as illustrated, a conduit 22 is run from the atmosphere side of thethrottle valve-equipped carburetor to the upper rear end portion of thecrank-case 4', and conduits 23 are provided for connecting the front topportion of the crank-case to the intake at the engine side of thethrottle valve-equipped carburetor. The conduit 22 is coupled to theintake neck 9a. of thecarburetor and opens into the base ll" of thefuelpump H so as to communicate with the crank-case through the base ofthe fuel pump and the filler neck. The conduits 23 are in the nature ofsmall holes in the walls of the intake manifolds 6 and 6. With theconnections thus made, the conduits 22 and 23 will both be subject tovacuum or subatmospheric pressure under all operating conditions, butthe conduits 23 will be subject to greater vacuum or more greatlyreduced pressure than the conduit 22 by virtue of the air restrictionoffered by the throttle valve-equipped carburetor. This restriction setup by the carburetor, while always existent to some extent, will be atmaximum when the throttle valve is closed and will be at a minimum whenthe throttle valve is open.

When the engine is operating at idle or slow speed, the throttle valvebeing now closed, will greatly restrict the intake and the resultantdifferencein vacuum or pressure between points of connection of conduits22 and 23 to the intake will be so greatly in favor of conduits 23 thatthe crank-case will be maintained under greater vacuum or lowersub-atmospheric pressure than that existent in conduit 22, and this inspite of the normal piston blow-by gases, which latter tend to raise thepressure in the crank-case. Under these conditions, not only will theblowby gases be rapidly removed from the crank-case, but the saidblow-by gases will be instantly di luted with clean air now rapidlycirculated through the crank-case. This dilution of the gases with cleanair raises the dew point temperature of the mixture to a point where itwill easily hold its fuel and water vapors during its brief stay in thecrank-case. In practice, it has been found practically impossible toremove undiluted-blow-by gases from a very cold crankcase withsuflicient rapidity to prevent condensation when the moisture-ladengases contact the cold metal parts, but by immediately diluting gasesand then rapidly removing the same, as above outlined, condensation isprevented under very severe conditions.

The condition above recited will continue to a varying extent throughoutthe most used engine speed range, although the difference betweencrank-case pressure and the pressure in the intake at the point ofconnection of conduit 22 will be reduced as the speed of the engine isincreased, such reduction being due to the following factors, to wit:(a) the reduction in intake vacuum or pressure differential betweenpoints of connection of conduits 22 and 23 to the intake, by virtue ofreduced intake restriction under increased opening of the throttlevalve; and (b) the inevitable increase in the volume of gases blown intothe crank-case under increased engine speed. At some point, usuallyquite high in the speed range and variable according to thecrosssectional areas and relative cross-sectional areas of conduits 22and 23 and the condition of the engine, the sub-atmospheric pressure inthe crank-case will rise slightly above that of the intake at point ofconnection of conduit 22 there'- to, although still remaining below thatof conduits 23. At this point, the circulation of engine intake airthrough the crank-case will cease, the movement of air through conduits22 reversing and now being from the crank-case to the intake. From thispoint upward to maximum engine speed, conduits 23 and 22 will functionjointly and collectively in withdrawing of blow-by gases from thecrank-case and through their joint operation, will retain the crank-casepressure well within safe limits and usually much below that prevailingunder like conditions in crank-cases vented by the conventional openbreather tube. Since, as before stated, engines are seldom run in thehigh speed range when very cold, condensation will be prevented by thisrapid removal of the gases without dilution by fresh air.

In this preferred application of the invention the restricted passages23 are formed axially through bushings 23a that are externally threadedinto and extend through the bottoms of the chambers or manifolds 6 and6'. There is a clean-out device for each restricted passage or conduit23, and in this preferred form each such clean-out device involves astern 24, to the lower end of which is attached a head or weight 25. Thestem 24 is preferably made up of two flat metal strips, the bodies ofwhich lie close together but the upper ends of which are turned outwardat 26 to form a sort of upper end head that normally rests on the upperend of the co-operating bushings 23a, but which do not close thepassages 23. The stem 24 is of such cross-sectional dimension that itdoes not completely close the passage 23 but does materially restrictthe small passage or conduit. Under normal or equalized pressures theclean-out device will be in its low- "ered position, indicated in thedrawing. When,

heads 26 will lift the cleaning devices to a greater or less extent butusually as far up as they can go. To prevent the weighted lowered ends25 from closing the passages 23 when the cleaning devices are raised,said heads or ends 25, as shown, are provided with lugs 21 that engagethe bottoms of the bushings.

Under the continually varying pressures in the manifolds or chambers thecleaning devices will be given vertical movements which effectuallyprevent accumulations in the restricted passages and keep the same clearof deposits. For the particular purpose above illustrated the cleaningdevices have been found completely satisfactory and highly efficient.However, they will be found eflicient in performing similar work invarious analogous devices, where small restricted passages or conduitsare required to work under conditions where, without continuouscleaning, such passages would be clogged in the course of usage.

In the particular use illustrated in the drawing, to get just the rightand properly regulated limited flow of air through the crank-case, itwas found that the size of the restricted passages or conduits washighly important and that that being so it was important that theconducting capacity of such conduits remain constant; or, in otherwords, that even partial clogging or limited accumulations of depositsin these conduits should be prevented. Obviously the device illustratedmeets all of these requirements.

A very simple form of clean-out device has been illustrated, but itwill, of course, be understood that such devices may vary greatlyinform. The clean-out device illustrated, however, is very cheap to makeand may be very easily applied and removed, repaired or replaced. Themetal strips of the stem 24 may be inserted through the bushings andtheir ends bent before the bushings areapplied. Of course, the devicewill be reof the maximum lifting action produced in the action of theengine by the pressure pulsations.

What I claim is:

1. In a device wherein two chambers are in communication through arestricted passage and are subject to varying pressure pulsationstending to produce varying flow through said restricted passage, aclean-out device working in said restricted passage and subject tomovement under such pressure pulsations, said clean-out devicecomprising a stem having a weighted lower end and a head at its upperend.

2. In a device wherein two chambers are in communication through arestricted passage and are subject to varyingpressure pulsations tendingto produce varying fiow through said restricted passage, a clean-outdevice working in said restricted passage and subject to movement undersuch pressure pulsations, said clean-put device having a splitor'divided stem weighted at its lower end and having the upper ends ofits two stem members bent outward in opposite directionsto form a head.

3. In a device wherein two chambers are in communication through arestricted passage and are subject to varying pressure pulsationstending to produce varying flow through said restricted passage, aclean-out device working in said restricted passage and subject, tomovement under such pressure pulsations, said restricted passage beingformed in a bushing and said cleanout device having a stem workingloosely through the restricted passage of said bushing, said stem havinga weight at its lower end and a head at its upper end.

4. The combination with an internal combustion engine having acrank-case and having an intake provided with a throttle valve therein,of a crank-case ventilating system comprising conduits extending fromthe intake at the opposite sides of the throttle valve and independentlyopening into the crank-case, one of said conduits having a restrictedpassage, and a clean-out device working in said restricted passage andsubject to movement under pressure pulsations.

5. The combination with an internal combustion engine having a sealedcrank-case and having an intake provided with a throttle valve therein,of a crank-caseventilating system comprising conduits extending from theintake at opposite sides of the throttle valve and independently openinginto the crank-case at points above the vice comprising a stem workingthrough said restricted passage, said stem having a weighted lower endand at its upper end a head that is subject to pressure pulsations,whereby the cleanout device will be reciprocated under varying partialvacuum or suction.

6. In a device wherein two chambers are in communication through arestricted passage and are subject to varying pressure pulsationstending to produce varying fiow through said restricted passage, aclean-out device working in said restricted passage and subject tomovement under such pressure pulsations, said cleanout device comprisinga stem of smaller diameter than said restricted passage arranged to workthrough said restricted passage and having a head at one end and aweight at its other end.

, 7. The combination with an internal combustion engine having acrank-case, and an intake wherein there is a varying degree ofsub-atmospheric pressure under operating conditions, of a crank-caseventilating system including a duct extending from the said intake tothe crank-case and having a restricted passage, and a clean-out deviceworking in said restricted passage and subject to movement underpressure variations in the intake, said clean-out device comprising astem of smaller diameter than said restricted passage arranged to workaxially there-through, and means for limiting axial movements of saidstem.

8. The combination with an internal combustion engine having acrank-case, and a combustion chamber air intake, of a crank-caseventilating system including a conduit extending from the intake to thecrank-case and incorporating a substantially vertically disposedrestricted passage, a clean-out device in the nature of a weighted stemof less diameter than said restricted passage working axially throughsaid restricted passage, and means for limiting axial movements of saidclean-out stem through the restricted passage under pressure variationsin the said intake.

9. The structure defined in claim 7 in which the said stem is weightedat one end.

, 10. The structure defined in claim 7 in which the said stem isweighted at its lower end.

'11. The structure defined in claim 8 in which the said stem is providedwith a weight at one end.

12. The structure defined in-claim 8 in which the said clean-out stem'isprovided with a weight at its lower end.

WIIJRED W. LOWTHER.

